The Islamic Republic responded to domestic unrest with unprecedented violence, slaughtering tens of thousands of people since protests broke out in late December.

Trump warned the regime not to kill protesters and vowed help was on the way. While he reportedly held off on an attack last month, the recent arrival of a U.S. aircraft carrier in the Middle East has raised expectations that a strike is imminent.

“We would put 75% odds in the coming days to weeks there will be some sort of U.S. attack on Iran,” Bob McNally, Rapidan Energy Group founder and former White House energy advisor, told CNBC on Thursday.

Brent crude oil futures have jumped 5% in the past week and 14% since the start of the year. Prices have now broken their yearlong pattern of a steady decline punctuated by brief spikes that quickly reverse to resume the downtrend, he noted.

The U.S. attack on Iran’s nuclear facilities last year resulted in only a temporary price surge as the conflict remained limited in scope and avoided the country’s oil infrastructure.

In addition, the U.S. military raid last month to capture Venezuelan dictator Nicolás Maduro failed to move the needle much in oil markets as production wasn’t interrupted.

“But this one is real,” McNally warned. “The markets are pricing the risk that this time the past will not indicate the future—that we could have a sustained disruption in energy flows.”

Iran pumped 4.7 million barrels per day last year, accounting for 4.4% of global oil supplies. Much of its heavily sanctioned shipments go to China via a so-called shadow fleet.

But the bigger risk centers on the potential for Iran to close off the Strait of Hormuz, where a fifth of all the world’s oil and liquefied natural gas (LNG) passes through on the way to export markets.

Markets assume that the U.S. Navy could quickly clear any underwater mines or other threats that would prevent tankers from traversing the Strait of Hormuz, but McNally thinks that’s a mistake.

He pointed out that the U.S. failed to completely pacify the threat from Houthi rebels, who attacked shipping in the Persian Gulf before Trump essentially reached a ceasefire agreement.

“Iranians have much better weaponry and a better coastline to harass that strait, so God forbid it comes to that,” McNally added.

On Sunday, Iran’s supreme leader warned that any attack by the U.S. would spark a “regional war” in the Mideast, marking the most direct threat he’s made so far during Trump’s military buildup in the area.

But sources told Axios that the Trump administration told Tehran through back channels that it’s open to meeting to negotiate a deal.

McNally on Thursday flagged the escalating rhetoric and highlighted the potential for upheaval in the LNG market in the event of an Iranian blockage of the strait.

“If it lasts more than one or two days, the market will be shocked because we simply can’t imagine a scenario where the U.S. military doesn’t prevail militarily [and] overwhelmingly in hours to days,” he predicted. “We just haven’t seen it in history, but it’s entirely possible. In that case, you will see the mother of all bidding on any spot cargoes for LNG.”